1. Field of the Invention
The present invention relates to a plasma display panel (PDP), and more particularly, to a PDP having a slanted pair of sustaining electrodes that face each other on a front substrate to generate efficient plasma discharges.
2. Discussion of the Related Art
A PDP, which uses electrical discharges to form an image, is a bright display with a wide viewing angle. In the PDP, applying a DC or AC voltage to the electrodes generates a gas discharge in a gas between electrodes, thereby creating ultraviolet rays that excite a fluorescent material to emit visible light.
Plasma display panels are classified into direct current (DC) and alternating current (AC) PDPs depending upon driving waveform shapes and discharge cell structures. In a DC PDP, the electrodes are exposed in a discharge space, and electrical charges directly moving between electrodes generate a discharge. On the other hand, in an AC PDP, at least one electrode is covered with a dielectric layer, and wall charges generate a discharge instead of the electrical charges directly moving between the electrodes.
Additionally, PDPs may be classified into facing and surface discharge PDPs depending on the arrangement of electrodes. In a facing discharge PDP, two sustaining electrodes provided on front and rear substrates, respectively, face each other, and a discharge is generated in a direction perpendicular to the substrates. On the other hand, in a surface discharge PDP, a pair of sustaining electrodes is provided on the same substrate, and a discharge is generated between the pair of electrodes and parallel to a surface of the substrate.
Although it has high luminous efficiency, plasma particles may easily deteriorate the facing discharge PDP's fluorescent layer. Therefore, the surface discharge PDP has been mainly used.
FIG. 1 and FIG. 2 illustrate a conventional surface discharge PDP. In FIG. 2, a front substrate 20 is rotated 90° in order to more clearly show an internal structure of the PDP.
Referring to FIGS. 1 and 2, the conventional PDP may include rear and front substrates 10 and 20 facing each other.
A plurality of address electrodes 11 is provided in stripes on an upper surface of the rear substrate 10. The address electrodes 11 are covered by a first dielectric layer 12 made of a white dielectric material. A plurality of partitions 13 is provided at a predetermined interval on an upper surface of the first dielectric layer 12 in order to prevent electrical or optical crosstalk between discharge cells 14. Red (R), green (G) and blue (B) fluorescent layers 15 having a predetermined thickness are coated on inner surfaces of respective discharge cells 14 defined by the partitions 13. The discharge cells 14 are filled with a discharge gas, which is typically a mixture of Ne and Xe.
The transparent front substrate 20 is may be mostly made of glass, allowing visible light to pass. The front substrate 20 is sealed together with the rear substrate 10 provided with the partitions 13. Stripe-shaped pairs of sustaining electrodes 21a and 21b are provided on a lower surface of the front substrate 20 and are orthogonal to the address electrodes 11. The sustaining electrodes 21a and 21b may be made of a transparent, conductive material such as indium tin oxide (ITO), which is capable of passing visible light. Metal bus electrodes 22a and 22b are provided on lower surfaces of the sustaining electrodes 21a and 21b to reduce the line resistance of the sustaining electrodes 21a and 21b. The sustaining electrodes 21a and 21b and bus electrodes 22a and 22b are covered by a transparent second dielectric layer 23. A protective layer 24, typically made of magnesium oxide (MgO), is provided on a lower surface of the second dielectric layer 23. The protective layer 24 prevents sputtered plasma particles from deteriorating the second dielectric layer 23, and it reduces discharge and sustaining voltages by emitting secondary electrons.
Driving schemes of the conventional PDP having the above structure may be classified as address and sustaining driving schemes. In the address driving schemes, an address discharge is generated between the address electrode 11 and one sustaining electrode 21a, to form wall charges. On the other hand, in the sustaining driving scheme, a sustaining discharge is generated by a potential difference between the sustaining electrodes 21a and 21b in a discharge space where wall charges are formed. Ultraviolet rays emitted from a discharge gas during the sustaining discharge excite the fluorescent layer 15 in the discharge cell 14 to emit visible light. The visible light passes through the front substrate 20 to form an image on the display.
In the conventional PDP having the above structure, a gap exists between the sustaining electrodes 21a and 21b in order to generate a highly efficient plasma discharge. However, if the gap is too wide, a sustaining discharge voltage increases. Additionally, an address discharge voltage must also increase in order to accumulate sufficient wall charges.